The goal of the proposed work is to anatomically and neurochemically define substrates in the brain that are critically involved in the rewarding property, and hence the abuse liability of cocaine and other psychomotor stimulants. Current evidence points to catecholamine mechanisms which also appear to subserve the rewarding effects of intracranial electrical stimulation, and parallel studies of intravenous cocaine reward and intracranial stimulation reward involve assessing the effects of selective catecholamine receptor blockers. Dopamine blockers appear to attenuate the rewarding impact of stimulation and of cocaine, while noradrenaline blockers have thus far shown no such effects in our hands. Mapping of self-stimulation with relation to catecholamine fluorescence is used to suggest the critical pathways, and lesion studies in self-stimulation and self-administration test the significance of the pathways suggested by self-stimulation mapping.